Another function pair required for serialisation; these ones save

and restore anything vitally important in the game_ui. Most of the
game_ui is expected to be stuff about cursor positions and currently
active mouse drags, so it absolutely _doesn't_ want to be preserved
over a serialisation; but one or two things would be disorienting or
outright wrong to reset, such as the Net origin position and the
Mines death counter.

[originally from svn r6026]

netslide.c

@@ -1005,6 +1005,15 @@ static void free_ui(game_ui *ui)
     sfree(ui);
 }
 
+char *encode_ui(game_ui *ui)
+{
+    return NULL;
+}
+
+void decode_ui(game_ui *ui, char *encoding)
+{
+}
+
 /* ----------------------------------------------------------------------
  * Process a move.
  */
@@ -1822,6 +1831,8 @@ const struct game thegame = {
     FALSE, game_text_format,
     new_ui,
     free_ui,
+    encode_ui,
+    decode_ui,
     game_changed_state,
     interpret_move,
     execute_move,